GENERAL CONSIDERATIONS I SHOULD like to open my remarks concerning therapy of cystic fibrosis of the pancreas by pointing out that some of the things we do are based on sound physiologic principles, such as salt and pancreatic enzyme replacement. Other therapeutic measures are based on prevention, e.g., the use of water-miscible vitamin A to prevent vitamin A deficiency, the use of vitamin K to prevent prothrombin deficiency, or the use of gamma-globulin to prevent measles in the exposed patient. A number of therapeutic measures have been employed in the management of patients with cystic fibrosis that require further evaluation, as unfortunately the effects produced in many instances are based on the judgment of anxious parents and enthusiastic physicians. Examples of this kind may include the use of trypsin by intramuscular or aerosol routes or the use of adrenal steroids. It is important to keep a proper perspective. We must not discard any form of therapy that offers relief, and on the other hand, we must avoid the use of harmful agents and needless operative procedures. The first point I should like to make is the importance of being certain of the diagnosis. In the case of equivocal laboratory findings with a clinical picture that is consistent with the disease, I believe therapy should be instituted and the laboratory tests repeated, until the diagnosis can be established or discarded. Figure 1 shows a 9-week-old baby who was first seen about 10 years ago. He had the typical pulmonary picture of cystic fibrosis, yet the duodenal fluid contained adequate proteolytic activity and showed increased viscosity.